To meet the requirements of high-speed broadband communication, optical communication industries that utilize light as a transmission medium have progressed rapidly. Optical fiber applications related to optical communication have also become increasingly important. To achieve the objectives of high-speed optical communication and expanded utilization, low cost optical communication devices and high speed transceiver modules are essential. Moreover, future development of data communication for high performance computers aims to employ optical interconnect to link computer chip sets, modules, circuit boards, base boards, cases and processors, and high speed photons for signal transmission to overcome the bottleneck of bandwidth limitations encountered in electron transmission. As the processing speed of the computer CPU or other chip sets becomes faster, the demand for using photons to transmit data also increases. When computer and communication techniques are coupled, optical connections and optical data communication between them become important issues.
Optical communication elements have to meet the requirements of installation environments that demand slim, light and high reliability. The conventional optical interconnection generally adopts direct coupling between a photoelectric element and an optical waveguide. Such an approach does not produce desired optical coupling efficiency and reliability. Researchers are trying to produce a microlens through a polymer structure to enhance the optical coupling efficiency and element airtight packaging. But alignment of the polymer microlens and other photoelectric elements is difficult.
U.S. Pat. No. 6,754,407 discloses a technique to solder a photoelectric element onto an integrated circuit (IC) through a flip-chip approach. Then the photoelectric element is aligned with an optical waveguide pore of a printed circuit board (PCB) through a flip-chip approach, and soldered on the PCB. The photoelectric element has a lens to increase the optical coupling efficiency with the waveguide of the PCB. Such a technique can reduce metal wiring on the PCB, improve signal transmission quality, and reduce the fabrication difficulty of embedding holographic optical elements (HOE) in the PCB waveguide, to serve as the optical signal transmission path and increase usage flexibility. However, such a technique involves soldering the photoelectric element directly onto the IC. When the IC is in operation, the heat generated by the IC is transferred directly to the photoelectric elements and impairs signal transmission quality. The technique also does not deal with how to package the integrated IC and photoelectric elements. Packaging to meet reliability requirements is also a challenge.
U.S. Pat. No. 6,603,915 discloses an interposer and method for producing a light-guiding structure that forms a waveguide on a circuit substrate and expands the waveguide through oxidation so that the waveguide in the substrate can be coupled directly with the photoelectric elements integrated on the IC without a through HOE or other elements. Thereby metal wiring on the circuit board may be reduced and signal transmission speed and quality increased. However, it also has the same reliability and cooling problems encountered in U.S. Pat. No. 6,754,407.